This invention generally relates to diamond polishing and adjusting devices, and more particularly to an improvement in a diamond faceting platform which assures continued positive engagement between a dop supporting worm gear and a manually operable worm engaged with the worm gear.
Various diamond polishing and adjusting devices are known which support dops and are adapted to selectively alter the position of the dop for successive cutting and polishing of diamond facets. Many of these diamond polishing and adjusting devices, or diamond faceting platforms, include gear arrangements which facilitate changing of the angular positions of a dop or diamond. In one known arrangement, a worm gear is provided which is in the form of a dop receiver or dop mounting member, a cooperating worm being provided which is accessible and manually operable. The worm of the known device engages the worm gear and rotation of the worm results in corresponding rotation of the worm gear about an axis substantially normal to the axis of the worm. In order to facilitate rotation of the worm within the platform structure, and considering manufacturing tolerances and wear, the bore in which the worm is disposed generally has a diameter greater than that of the worm. Accordingly, the worm is disposed within the bore with clearance and is generally movable within the bore in transverse directions towards and away from the worm gear.
The above described play between the worm and the worm gear is undesirable since it does not result in positive engagement between the two members and thereby results in a backlash or positioning error when the direction of the worm is reversed. In order to enhance the positive engagement between the worm and the worm gear, it has been proposed to utilize a leaf spring which bears against the worm and biasses the latter in the direction of the worm gear. This solution does not, however, solve the problem entirely since the leaf springs which are utilized are normally effective only over limited distance ranges and sometimes do not provide the desired biassing action at all positions of the worm. This is particularly true as the leaf spring approaches its unstressed condition and thereby applies smaller and smaller forces to the worm. Also, when the leaf spring is maintained in a flexed condition for a long period of time, it tends to lose some of its resiliency as it sets or begins to assume the deformed condition due to fatigue. In either case, the user has very little control over the degree of biassing or positive engagement of the worm with the worm gear once the platform is assembled.
The present devices eliminates the above described disadvantage in the use of the leaf spring and replaces this biassing arrangement with a pair of set screws which act upon low friction sleeves in which smooth end or shaft portions of the worm are journalled. The set screws provides a great degree of control and adjustability of the position of the worm relative to the worm gear to thereby permit positive engagement between the two members independently of manufacturing tolerances and wear. With the present arrangement, because the set screws act upon the low friction sleeves and not upon the worm itself, the worm is permitted to fully rotate within the sleeves and thereby actuate the worm gear and the dop supported thereon.